A new method named STM is described for determining distance of object
s and rapid autofocusing of camera systems. STM uses image defocus inf
ormation and is based on a new Spatial-Domain Convolution/Deconvolutio
n Transform. The method requires only two images taken with different
camera parameters such as lens position, focal length, and aperture di
ameter. Both images can be arbitrarily blurred and neither of them nee
ds to be a focused image. Therefore STM is very fast in comparison wit
h Depth-from-Focus methods which search for the lens position or focal
length of best focus. The method involves simple local operations and
can be easily implemented in parallel to obtain the depth-map of a sc
ene. STM has been implemented on an actual camera system named SPARCS.
Experiments on the performance of STM and their results on real-world
planar objects are presented. The results indicate that the accuracy
of STM compares well with Depth-from-Focus methods and is useful in pr
actical applications. The utility of the method is demonstrated for ra
pid autofocusing of electronic cameras.